There’s a few threads on here discussing it. I’ve done about 1200 miles with no issues, loving the lack of maintenance\cleaning, it’s quiet, has enough range if you gear it right and it’s nice and quiet. Downside is 2lb extra weight but it feels balanced with my front end.
groove containing the gear cable on the hub got gunged up and affected the indexing
That’s only issue I’ve had (2 or 3 times), but you recognize it after the first time and it’s only been in horrendous slop where everyone else with a normaly geared setup has had to clear the crap from there mechs etc.
The first batch were bad, but long gone now. From what I’ve been told.